The present disclosure relates to an acceleration sensitive indicator for indicating the application of an acceleration field, a sample container comprising the indicator for centrifuging a biological sample contained therein, and an analytical system for determining the centrifugation status of the sample.
Proper analysis of a biological sample can depend on the centrifugation status of the biological sample, and thus it is often important to determine whether centrifugation to separate various sample constituents has already been accomplished or not. Not only can a lack of completed centrifugation affect the validity of an analytical test, but additional, unnecessary centrifugation applied to a sample may have a negative impact on the quality of an analysis performed on that sample. For example, many sample tubes used for preparing plasma or serum from whole blood samples comprise a gel for stably keeping the sediment (which can comprise sedimented cells, a particular sedimented cell fraction, a sedimented clot, and the like) separated from the serum or plasma after centrifugation. If one or more additional centrifugation steps are carried out on the already centrifuged sample, the gel barrier may be damaged, thereby allowing the sediment and serum or plasma to mix. Thus, it is important to be able to determine whether a sample, e.g. whole blood, which is not supposed to be centrifuged for certain types of diagnostic tests, has been accidentally centrifuged or whether a sample, e.g. plasma or serum, that is supposed to be obtained from whole blood under particular centrifugation conditions, has not been centrifuged at all or has been centrifuged under inappropriate centrifugation conditions.
Various approaches to automate the task of detecting whether a biological sample container has been centrifuged have been developed: in some laboratories, an Information Technology system (“IT system”), e.g., a LIS or laboratory middleware system, is used to control a laboratory workflow and keep track of the current centrifugation status of one or multiple biological samples. However, the amount and type of data managed by a laboratory's IT-system, varies between different laboratories. Many laboratories, in particular smaller ones, currently do not integrate data related to the centrifugation state of the samples.
In other laboratories, the centrifugation status is determined by visual inspection or using imaging-systems. Manual and image-system based approaches are both error prone. In the case of blood samples, for example, a slight separation effect can be observed when a biological sample is left to stand for one hour or longer. As a consequence, simple visual inspection and image-system based approaches in many cases will wrongly interpret this naturally occurring separation effect as the result of an applied centrifugation step. Since the upper part of a blood sample naturally becomes transparent upon sitting in an upright orientation, an optical detector cannot distinguish reliably between a properly centrifuged sample and a plasma sample with naturally occurring sedimentation.
Therefore, there is a need for an acceleration sensitive indicator that indicates whether a sample has been centrifuged as well as permits detection of centrifugation quality in order to enhance the reliability of diagnostic tests and that is simple, cost effective and provides enhanced stability of the readout after centrifugation, an internal quality control of the centrifugation status readout and a readout that discriminates between swing-type and fixed angle type centrifuges.